The present invention, a combined tape cleaner/rewind foot, relates to the field of cleaning the magnetizable surface of magnetic tape in a tape transport system and to the field of reducing wear on the tape and the read/write head during rewind operation, and in particular, to combining the two functions into a single, dual function unit.
In modern magnetic tape transport systems, the ability to store ever increasing amounts of digital data has been required. To accomplish this, decreased tape-read/write head separations have been needed. As this separation distance decreases, the problems associated with foreign matter on the tape surface has increased. In the prior art, small dust or oxide particles which would not have caused a read/write problem, will now cause significant errors as the separation distance between the head and the tape exceeds 2 microinches.
In the prior art, the tape has generally been cleaned by such methods as blowing a stream of compressed air across the tape surface, see e.g. U.S. Pat. No. 3,097,779 issued to Rock et al, or by scraping the material from the tape surface with a sharp edge and then lifting the material away from the tape, such as by trapping the particles in a porous material, see e.g. U.S. Pat. No. 3,975,789 issued to Derby et al, and U.S. Pat. No. 3,978,546 issued to Epina et al. However, new technology has generated much more delicate magnetic tapes so that use of the prior art cleaning methods would be ineffective in removing the smaller foreign matters and could severely wear and damage the sensitive recording materials. The present invention addresses this problem by providing a cleaning screen that gently loosens the foreign material and then removes the foreign material from the tape by use of negative pressure applied through the holes in the screen to the tape surface.
Another problem encountered in magnetic tape transport systems has been wear on both the read/write head and the tape itself during rewind operations. In modern tape transport systems, the tape can reach speeds of up to 500 inches per second during a rewind operation. If the tape were allowed to contact the read/write head during rapid rewind, in a relatively short time, both the head and the tape would be severely worn. The prior art has addressed this problem by establishing hydrostatic bearing surfaces using forced air to provide the air cushion upon which the tape floats during rewind. However, the prior art using this technique require positive pressure in the system in order to support the tape. These systems can be quite complex and are subject to a number of operational defects.
The present invention addresses this problem by using a tape foot which, when placed in the tape path as the rewind operation begins, lifts the tape away from both the cleaner screen and the read/write head. The tape foot is also a hydrodynamic bearing, using the aerodynamic shape of the tape foot surface to allow the air pressure between the tape and the tape foot to cause the tape to lift away from the tape foot and float on an air cushion as tape rewind speed is reached. An improvement over the prior art is also achieved in that special pressurization is not needed.
In addition, in magnetic tape transport systems, proper alignment of the tape as it passes over the read/write head is essential to proper system operation. The closer the tape guides can be placed to the read/write head, the more accurate will be the alignment. In the prior art, the tape cleaner and the rewind foot have been two seperate units. The present invention is an improvement over the prior art in that the tape cleaner and the rewind foot have been combined into a single unit. Thus, the space that in the prior art was occupied by two units is now occupied by a single cleaner/tape foot unit. This in turn allows the tape guides to be placed closer to the read/write head, thus providing for a more accurate tape alignment and tracking.
It is an object of the present invention to provide a means for cleaning magnetic tape as it moves through a magnetic tape transport system.
It is a further object of the present invention to provide a means for reducing wear to the read/write head in a magnetic tape transport system.
It is yet a further object of the present invention to provide a means for reducing the wear to the tape itself in a magnetic tape transport system.
It is still yet another object of the present invention to provide a means for combining the function of a tape cleaner and a rewind tape foot into a single unit.
And it is still yet a further object of the present invention to provide a means for improving the alignment of the tape with respect to the read/write head as the tape moves in a tape transport system.